TY - JOUR
T1 - Coevolution of an aminoacyl-tRNA synthetase with its tRNA substrates
AU - Salazar, Juan C.
AU - Ahel, Ivan
AU - Orellana, Omar
AU - Tumbula-Hansen, Debra
AU - Krieger, Robert
AU - Daniels, Lacy
AU - Söll, Dieter
PY - 2003/11/25
Y1 - 2003/11/25
N2 - Glutamyl-tRNA synthetases (GluRSs) occur in two types, the discriminating and the nondiscriminating enzymes. They differ in their choice of substrates and use either tRNAGlu or both tRNAGlu and tRNA Gln. Although most organisms encode only one GluRS, a number of bacteria encode two different GluRS proteins; yet, the tRNA specificity of these enzymes and the reason for such gene duplications are unknown. A database search revealed duplicated GluRS genes in >20 bacterial species, suggesting that this phenomenon is not unusual in the bacterial domain. To determine the tRNA preferences of GluRS, we chose the duplicated enzyme sets from Helicobacter pylori and Acidithiobacillus ferrooxidans. H. pylori contains one tRNAGlu and one tRNAGln species, whereas A. ferrooxidans possesses two of each. We show that the duplicated GluRS proteins are enzyme pairs with complementary tRNA specificities. The H. pylori GluRS1 acylated only tRNAGlu, whereas GluRS2 was specific solely for tRNAGln. The A. ferrooxidans GluRS2 preferentially charged tRNAGln UUG. Conversely, A. ferrooxidans GluRS1 glutamylated both tRNA Glu isoacceptors and the tRNAGlnCUG species. These three tRNA species have two structural elements in common, the augmented D-helix and a deletion of nucleotide 47. It appears that the discriminating or nondiscriminating natures of different GluRS enzymes have been derived by the coevolution of protein and tRNA structure. The coexistence of the two GluRS enzymes in one organism may lay the groundwork for the acquisition of the canonical glutaminyl-tRNA synthetase by lateral gene transfer from eukaryotes.
AB - Glutamyl-tRNA synthetases (GluRSs) occur in two types, the discriminating and the nondiscriminating enzymes. They differ in their choice of substrates and use either tRNAGlu or both tRNAGlu and tRNA Gln. Although most organisms encode only one GluRS, a number of bacteria encode two different GluRS proteins; yet, the tRNA specificity of these enzymes and the reason for such gene duplications are unknown. A database search revealed duplicated GluRS genes in >20 bacterial species, suggesting that this phenomenon is not unusual in the bacterial domain. To determine the tRNA preferences of GluRS, we chose the duplicated enzyme sets from Helicobacter pylori and Acidithiobacillus ferrooxidans. H. pylori contains one tRNAGlu and one tRNAGln species, whereas A. ferrooxidans possesses two of each. We show that the duplicated GluRS proteins are enzyme pairs with complementary tRNA specificities. The H. pylori GluRS1 acylated only tRNAGlu, whereas GluRS2 was specific solely for tRNAGln. The A. ferrooxidans GluRS2 preferentially charged tRNAGln UUG. Conversely, A. ferrooxidans GluRS1 glutamylated both tRNA Glu isoacceptors and the tRNAGlnCUG species. These three tRNA species have two structural elements in common, the augmented D-helix and a deletion of nucleotide 47. It appears that the discriminating or nondiscriminating natures of different GluRS enzymes have been derived by the coevolution of protein and tRNA structure. The coexistence of the two GluRS enzymes in one organism may lay the groundwork for the acquisition of the canonical glutaminyl-tRNA synthetase by lateral gene transfer from eukaryotes.
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U2 - 10.1073/pnas.1936123100
DO - 10.1073/pnas.1936123100
M3 - Article
C2 - 14615592
AN - SCOPUS:0344270891
SN - 0027-8424
VL - 100
SP - 13863
EP - 13868
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - SUPPL. 2
ER -